Taking an observation at the pole

One problem that arriving
at the South Pole posed was determining exactly where it was.
The pole itself is on a featureless icy plateau. The ice above
it is moving continually but slowly. Only by very careful repeated
navigational readings could Amundsen's team actually determine
that they had arrived.

Thus they established that this flat white
bit was the pole as opposed to that other flat white bit, they
passed over half an hour ago.